This is Not OE

When you check Monarchs and Queens for OE, what do you see on the slide besides OE?

When one has never seen OE spores through a microscope, it may be confusing to look for spores. There can be other ‘things’. What are they? Here are photos of a few items found when looking through a microscope. First, three photos of OE spores.

OE spores are perfectly shaped, a pointed oval, like a football. Over 100 can fit on one butterfly scale. (Learn how to check Monarch and other Danaus sp butterflies here.)

Note: a few spores may be on only part of the slide. Not all OE infected butterflies have as many scales as those that were used for these photos.

If the butterfly was wild-caught or flying around flowering plants, some ‘things’ may be pollen picked up from the flowers from which they were drinking nectar. Although some types of pollen resembles OE spores, note that pollen particles are not smooth football shapes.


Other than pollen, dust will stick to the abdomen of a butterfly if it emerges in a room. Landing on windowsills, tops of bookcases, and other dusty spots causes these particles to stick to the butterfly. Note that the shape of dust particles are not smooth football shapes.


When taped, a butterfly may pee at the same time. When pee or liquid touches scales, the scales become clear.

CLEAR tape should be used to check for OE. “Transparent” tape isn’t clear. The first photo below shows OE spores through clear tape. The second photo is of OE spores from the same butterfly through “transparent” tape. The third photos shows OE spores through both clear and “transparent” tape. Clear tape is obviously clear on the upper left in the photo and “transparent” tape in the lower right of the photo.
If you would like someone to check some slides or tape for you, please send your tape (clear tape) and email address to:
OE Check
9702 SW 128th Place
Brooker, FL 32622

If you would prefer to remain anonymous, don’t use a return address and give us a temporary email address to write you after we check the tape. No names or identification is needed. We DO need some type of contact information to tell you the results!

This offer is simply to help people who are raising butterflies at their farm, in their school, or in their homes. We are not tracking OE. If you would like to participate in the University of Minnesota’s OE studies, please check out The Monarch Larvae Monitoring Project.